> [EMAIL PROTECTED] wrote: > > > "Wacom Products Modified RG-214 Double shielded" on it, > > > it is an untinned double shielded cable > > Are the shields the same exact material makeup... or is > > one copper and the other something else?
> They are both copper. Nothing wrong with both shields being copper... > You're preaching to the choir. I think untinned double shielded > copper is very adequate to duplexer connections. But there are > contributors aboard who feel that silver plated shields are a > better choice. Normally the silver plated stuff is newer and is reported to have less loss. But as long as you keep moisture out of the copper jacket double shield it should continue to work very well for many decades. I have some 1970's and 1980's vintage copper double shield still considered very nice coax that doesn't generate pim. In fact the slightly higher loss over rg-214 acts as a modest value pad at some very noisy locations. So there can be a quite viable place for everything... > > I've actually seen that duplexer... :-) > Hey you, get your cottin pickin hands outta that cabinet! Just a crank here and a screw driver there... and if you looked across the vault I was the 800 MHz community repeater in the same room (now long gone). > I queried Lloyd Alcorn regarding this in the 80s and he > indicated that he was hard pressed to improve the tracker > curves using different TX and RX cables on a 600KC VHF > split. The cables supplied for the sets he supplied me > all had identical 12.5 inch length cables. But I can actually see the difference in the cable quality with mid 90's vintage hp gear... hence the reason my same duplexer tx cable is reduced in length by about 3/8 inch. Later I could review my notes and let you know the exact values but you'd have to change to mil spec rg-214 cable. :-) > That's interesting. Perhaps both loony groups are correct. > You can't do much about an impedance mismatch between a > connector and an associated cable because the cable has > a fixed nominal impedance. Depends on the connector... In some high powered rf amplifiers I actually "tune the connector" where required or replace it with one that doesn't require any changes. The latter being much easier... > But the chassis connector impedance mismatch can be accounted > for by the network that feeds it. Didn't Motorola use UHF > connectors on their equipment for decades and their position > was that the impedance mismatch was accounted for. not enough of an issue to get excited about or fairly easily worked around. > I remember Hank Edwards at Phelps Dodge commenting that when > they designed their sticks, they accounted for UHF cable > and chassis connector mismatches in the antenna design itself. can be done... > K7IJ See you at one of those flea markets this summer from that list I sent you... "You need more stuff anyway" cheers, skipp
